1. Field of the Invention
The invention relates generally to a novel high power, high frequency solid state oscillator.
2. Related Art
Microwave solid state oscillators are described in various textbooks including "Microwave Solid State Circuit Design," written by I. Bahi and P. Bhartia (Wiley-Interscience Publication, 1988, Chapters 3 and 9) and "Microwave Circuit Design Using Linear and Nonlinear Techniques," written by George D. Vendelin, Anthony M. Pavio, and Ulrich L. Rohde (Wiley-Interscience Publication, 1990, Chapter 6). Articles on such oscillators include "Microwave Solid State Oscillator Circuits," written by K. Kurokawa (Microwave Devices, Wiley, 1976) and "Accurate Linear Oscillator Analysis and Design," written by J. L. Martin and F. J. Gonzales (Microwave Journal, June 1996 pp. 22-37).
Microwave oscillators utilizing solid state components and strip-line transmission lines are described in U.S. Pat. Nos. Re 32,527, 4,736,454, and 5,339,047. Solid state microwave oscillators having various feedback structures are described in U.S. Pat. Nos. 4,775,845, 4,906,946, 4,949,053, and 5,483,206.
Conventional solid state microwave oscillators produce relatively low power output, for example, ranging from a few hundred milliwatts (mW) up to a few watts (W) at most. Moreover, conventional solid-state microwave oscillators are relatively inefficient, typically less than 40%.
For higher power applications requiring a high frequency signal, the oscillator signal is typically provided to an amplifier to increase the output power. For example, FIG. 1 is a schematic diagram of a conventional system for providing a high power, high frequency signal. An oscillator 702 provides a low power, high frequency signal to an amplifier 704 which increases the power level and outputs a high power, high frequency signal.
A radio frequency (RF) powered electrodeless light source is one example of an application which could utilize a high power, high frequency signal source. For example, U.S. Pat. No. 4,070,603 discloses an electrodeless light source which is powered by a solid state microwave power source. The microwave power source described therein has the general structure shown in FIG. 1. Namely, the output of a relatively low power oscillator is applied to a power amplifier to provide a 40 W, 915 MHz signal, at a purported 50% direct current (DC) to RF efficiency.